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H. A. WRENN CALCULATING MACHINE Filed Aug. 16 1921 2 Sheets-Sheet? Patented Jan. 15, 1924.

UNITED STATES PATENT OFFICE.

HERBERT A. WRENN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE WRENN ADDING MACHINE COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

CALCULATING MACHINE.

Application filed August 16, 1921. Serial No. 492,761.

To all whom it may concern: 1

Be it known that I, HERBERT A. WRENN, a citizen of the United States, residing at Washington, in the District of Columbia,

I have invented certain new and useful Improvements in Calculating Machines, of

which the following is a specification.

This invention relates to calculating machines, and more particularly to improvements in transfer mechanism therefor.

Ina copending application, Serial No. 205,517, filed June 20, 1919, I have disclosed and claimed a calculating machine wherein a plurality of numbering wheels are mounted 1 on a shaft and provided with chains passing over the wheels. When a number is to be entered into the machine, the chains are moved downwardly a distance corresponding to the number and the numbering wheels revolved. In the said application, I have further disclosed means for transferring a number from one column to the next upon each complete revolution of a wheel. The present application relates to improvements in the transfer mechanism whereby overrunning is prevented. The transfer mechanism includes a transfer rod which is adapted to engage the chain of the number wheel to the left and move it one unit. To

prevent the number wheel from being moved too far, I provide a pivoted, weighted lever arranged adjacent the chain and normally disengaged therefrom, but adapted to be moved into operative position by the movement of the transfer bar to engage one of the links of the chain and prevent itfrom being moved a greater distance than the distance necessary to add one unit on the wheel.

In the accompanying drawings, I have shown one embodiment of the invention. In

this showing:

Figure 1 is a vertical sectional view of a calculating machine showing the invention applied,

Figure 2 is a plan view of a portion of the operating mechanism,

Figure 3 is a side elevation of the transfer mechanism and a portion of the chain, and,

Figure 4 is a detail perspective view of the transfer mechanism.

Referring to the drawings, the reference numeral ldesignates a suitable casing having an inclined front wall 2. The front wall is provided with slots 3, similar to the slots shown in the copending application, and a chain 4 is arranged in each slot. The chain is adapted to pass over a number wheel 5 mounted on a shaft 6, the wheel being provided with suitable recesses 7 to receive the transverse bars 8 of the chain and revolve the wheel when the chain is moved. The casing is provided with openings 9 arranged in alinement with the number wheels whereby the numbers appearing on the wheels may be read. Suitable means (not shown) may be provided to prevent the wheels from revolving in a reverse direction.

The lowen end of the chain passes over a pin or rod 10 which serves to pivotally connect the upper and lower parts 11 and 12 of a checking device, serving to prevent overrunning of the chains. The up er part of the checking device is substantially U- shaped and comprises a. pair of arms 13 connected by a transverse plate 14 extending over the chain. The spacing and supporting strip 15 is arranged adjacent the lower part of the checking device. This spacing strip is adapted to enter notches 16 formed in the lower part of the checking device and serve as a pivotal support therefor. A spring 17 is connected to the end of the lower part of the checking device, the other end of the spring being anchored in any suitable manner to a stationary bar 18 arranged in the machine. The spring 17 normally tends to swing the checking device downwardly thereby retaining the operating chain taut. As the chain is moved, the engagement of the chain and the pin 10 tends to swing the checking device upwardly, and if the checking device is restrained from upward movement, advancement of the chain is prevented. The upper art of the checking device is provided wit a plate 19 extending upwardly and entering the bottom of the slot 3. When a pencil or stylus reaches the bottom of a slot, the engagement with the plate 19 moves the checking device downwardly and prevents further movement of the chain, thus preventing overrunning.

The transfer mechanism comprises a cam 20 carried by each number wheel having a high point 21 and a low point 22. A shaft 23 extends transversely of the machine substantially parallel to the main shaft and is adapted to support a plurality of L-shaped levers 24:. One of these levers is provided for each number wheel, each of the levers having a lug or pin 25 adapted to ride upon the cam. A transfer rod26 is secured to each of these levers, the rod being provided with an ofi'set portion 27 whereby the lower end 28 of the rod is arranged to the left of its corresponding number wheel and is adapted to cooperate with the chain of the number wheel to the left. The transfer rod is supported on a transverse rod or shaft 29. A. hook 30 is arranged on the lower end of the transfer rod and is adapted to be positioned between the links of the chain engag ing the cross member 8. A lever 31 is pivotally mounted on a transverse shaft 32, the lever being provided with an arm 33 adapted to be engaged by the offset portion 27 of the transfer bar when the transfer bar is moved downwardly. The lever is further provided with a dog 34, adapted to be received between the links of the chain when moved upwardly (see Figure 1). The lever is provided with a depending end 35 of sufficient weight to normally retain the dog in the lowered, dotted line position shown in Figure 1 of the drawings. A rod 36 is arranged adjacent the shaft 32 and is adapted to engage the arm 33 and the dog 34: to prevent them from moving more than a predetermined distance in an upward direction.

The operation of the device is as follows:

The normal operation of the machine is the same as disclosed in the copending application. The numbers to be added are entered on the machine by drawing the chains 4 downwardly a corresponding distance. As each number is entered into the machine, the plate 19 is engaged by the stylus or pencil and the transfer mechanism moved downwardly, preventing overrunning. As the number wheel revolves, the lug or pin 25 rides around the cam. At the end of each complete revolution, the pin reaches the high point 21 of the cam and moves to the low point, rocking the lever 24 on its pivot and moving the transfer bar 26 downwardly. When the transfer bar moves downwardly, the hook 30 engages one of the cross bars 8 of the chain to the left and moves it one unit.

The lever 34 prevents the chain to the left and its associated number Wheel from being moved more than a single unit. This memher is normally in the position shown in dotted lines in Figure l of the drawings, with the arm 33 arranged on the outside of the chain and the dog 34larranged below the chain. When the arm 33 is engaged by the offset portion 27 of the transfer bar, the lever is swung on its pivot to the full line position, and the dog 34; moved upwardly to engage a cross bar 8, and prevent the chain from moving mor than one unit.

It is to be understood that the form of the invention herewith shown and described is to be taken as a prefererd example of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. A transfer mechanism for calculating machines comprising a transfer bar, means for actuating said bar, and a pivoted lever mounted in the path of the transfer bar, said lever being adapted to be engaged by the transfer bar and swung on its pivot to engage a portion of the calculating mecha nism.

2. A transfer mechanism for calculating machines comprisng a movable transfer bar, a supporting rod arranged adjacent the transfer bar, and a lever pivotally mounted thereon, said lever being provided with an extension normally holding it in lowered position, but being adapted to be raised by the transfer bar to engag a portion of the calculating mechanism.

3. A. transfer mechanism for calculating machines, comprising a movable transfer bar having an offset portion, and a pivoted lever mounted in the path of the transfer bar adapted to be engaged by the offset portion thereof to move the lever into engagement with a portion of the calculating mechanism.

4. A transfer mechanism for calculating machines comprising a movable transfer bar, a pivoted lever mounted adjacent said transfer bar, and an arm carried thereby, said arm being adapted to be engaged by the transfer bar to move the lever into engagement with a portion of the calculatig mechanism. v

5. A transfer mechanism for calculating machines comprising a movable transfer bar, a pivoted lever mounted adjacent the transfer bar, said lever being provided with an arm adapted to be engaged by the trans fer bar, and a dog secured to said lever adapted to engage a portion of the transfer mechanism.

6. A transfer mechanism for calculating machines comprising a movable transfer bar having an ofiset portion, a supporting rod mounted adjacent said bar, a lever pivotally of the calculating mechanism when the mounted thereon, said lever being provided transfer bar is actuated.

ith an arm d t d t b engaged by the In testimon whereof I aflix my signature transfer bar and being provided with an in presence 0 two Witnesses.

extension adapted to maintain said arm in HERBERT A. WRENN. raised position, and a dog carried by said Witnesses: lever normally disposed in lowered position, J- DUNN AW, and adapted to be raised to engage a portion MABEL CLOPTON. 

